In today's highly mobile society, wireless communications have become increasingly prevalent and important for both personal and business uses. These wireless communications include paging services and other transmissions of data at least partially over wireless communication systems. Most widely recognized in this field, however, is the use of wireless telephones for voice communication.
Focusing specifically on voice communications, and what are commonly referred to as cellular telephones, there is no hard wired connection between the handset at the user location and the communication infrastructure. A radio signal is utilized for transmission over at least the wireless communication paths between the user hand piece and a receiving and transmitting device typically embodied in an elevated antenna. As will be well understood by those familiar with wireless communication systems' designs and implementations, aerial towers are dispersed about the landscape and conversations are "handed-off" between adjacent "cells" as a user travels a path across one or more coverage areas. The construction and configuration of individual towers varies based on local requirements. Antennas may be located upon existing buildings or topographically elevated sites, or they may be elevated upon an aerial tower similar to those used for the elevation of other utilities. In the instance of individual aerial towers, it is not unusual for their height to run from as little as forty feet to as much as five hundred or more feet.
Wireless communications, and particularly cellular voice service, is currently accommodated through the use of at least two varieties of antennae. Each is mountable upon the aerial towers previously described but have different operational and performance characteristics. Still further, antennae of various designs may be dictated by the mode of data communication such as analog and digital transmission.
One device used for transmitting and receiving these wireless transmissions is a panel antenna. These antennas are typically rectangularly box-shaped and generally, but not required to be configured to have widths between four and twenty inches, thicknesses between four and eight inches, and heights ranging between two and eight feet. These panel antennas are most often arranged in arrays that collectively are configured to cover generally pie-shaped areas that may extend over one hundred and twenty degree sectors. Individually, a panel antenna typically covers a tear-shaped or lily pad-shaped area. In use, these coverage areas, however, are normally altered or tailored by tilting and focusing the antenna downward and toward a specific service area.
Within each array is at least one transmit and one receive antenna. In the instance of analog transmissions, three sectors, each one hundred and twenty degrees in span, are utilized thereby requiring three antennas arrays to be appropriately configured to cover a three hundred and sixty degree zone about a tower's location. To accommodate the necessary three arrays of panels, the supporting platform and associated framework upon the aerial tower is typically three-sided or triangularly shaped.
This configuration can be contrasted with digital communications through panel antennas or antenna arrays which may span ninety degree coverage sectors thereby dictating the utilization of four panel antennas for full radial service about the tower. If four such panel arrays are utilized, the configuration of the support platform then changes from a triangular shape to a square shape for accommodating the four panels. When panel antennas are utilized, mobile phone calls are handed off between coverage zones as a user passes from one cell into another. There is normally a slight overlapping in the coverage zones so that uninterrupted conversation is made possible. The design of the panel antenna also facilitates high user densities, but in a relatively localized service area.
The second type of antenna is generally referred to as an omni-directional antenna and instead of being box shaped, the omni-directional antenna normally takes the form of an elongate cylinder. The visible exterior appearance of the omni-directional antenna is established by a sheathing which may be constructed from poly vinyl chloride pipe or similar elements. The actual transmit and receive antenna structures are contained within the sheathing; typically with transmit antennas pointed upward and receive antennas pointed downward. Each antenna has the capability to cover a three hundred and sixty degree circular service area.
As described above, a mobile telephone call is typically handed-off between panel antennas from one service area to the next based on travel path. The omni-directional antenna passes a call from one antenna to the next, instead of from one coverage area to the next. Therefore, the omni-directional antenna is typically aimed from one tower to another and these aimings may change on a frequent basis based on service requirements and new facility installations. The omni-directional antenna has a significantly greater capability for enlarged coverage areas over the panel antenna, but they are not as well suited to high user densities or traffic as is the panel antenna. Therefore, selection criteria between antenna design, as indicated above, is based at least in part on user densities and required coverage area. As a result, panel antennas are normally selected for urban uses or high traffic areas such as interstates, while omni-directional antennas are often used in rural settings where larger coverage areas are needed, but there are fewer users and less traffic in the service zone.
As addressed above, it is not uncommon for user requirements to dictate changes in antenna configurations on a regular basis. This creates discontinuous service situations and significant expense to the owner and administrator of the wireless system. Based on current designs, regardless of an antenna's type, it is fixedly mounted upon a platform structure of an aerial tower. Presently, pedestal-styled platforms are mounted upon a spindle column that is connected to the tower's upper end by mating bolted flanges. Antennas may also be supported individually or in groups on arm attachments to an elevating pole; but according to present designs, those arm are not positionally adjustable, but instead are fixed. The current method by which the orientation of a particular antenna is adjusted is to unbolt the mated flanges and rotate the entire platform to another boltable position wherein the uniformly spaced holes of the two flanges mate-up again. Obviously, this type of configuration prevents setting positions between such discrete and specifically defined boltable positions. In an effort to enhance this method for varying and adjusting the platform's position, the bolt holes of flanges of currently designed platforms have been slotted. These slots, however, are not continuous about the flange and therefore adjustability is compromised.
Of equal importance is the fact that each reconfiguration or reaiming of one or more antennas of a platform assembly becomes a substantial undertaking with respect to both man hours and required equipment. Typically, a crane will be necessary to support the platform while disconnected from tower's top flange. This requires a crew to be dispatched not only for the crane's operation, but also for the disconnection, rotation and reconnection of the platform itself. This demand for personnel and the associated expense is accentuated by the fact that this type of reconfiguration of the platform additionally requires the disconnection of the antenna, and consequently user service. This is a highly undesirable situation for the service provider since users are not able to use the network and no revenue is derivable during the reconfiguration time period. As a result, these procedures are often undertaken at night when user utilization is at its lowest, but personnel charges are most expensive.
Another aspect which must be dealt with in the design of an aerial tower for such purposes is the location and configuration of the associated shelter positioned adjacent to the base of the tower and within which the driving radio frequency equipment is housed for the wireless portions of the network. Normally, communication wiring is run from the antenna located atop the tower through the interior of the tower's pole or support column to a lower exit port through which the wiring passes to the shelter. A design criteria for this exit port and connection to the shelter is that it be as direct as possible without turns and angles. Based on the inflexibility of known systems, the position of the shelter is often dictated by the required orientation of the tower. As a result, the shelter is not always positionable in the most advantageous ground location proximate to the tower. Therefore, by accommodating continuous adjustability in the positioning of individual antennas atop the tower, restrictions in the design at the base of the tower will be removed.
In light of these highlighted and other deficiencies in present aerial tower designs for wireless communication antennas, the present invention has been developed in response thereto.